Coating apparatus



Mardi 20 1945. T. J. RADCLIFFE 2,372,118

COATING APPARATUS Filed April 2:5, 194s' :s sheets-snm 1 T. J. RADCLIFFECOATING APPARATUS 5 Sheets-Sheet Filed April 23, 1943 Aww March 20, 945.T 1 RADCLlFF-E 2,372,118

GOATING APPARATUS Filed April 23, 1945 3 Sheets-Sheet 3 Fig 4. i @Z HisAftftoneg.

Pnenfea M.r.zo,1s4s Y ooA'r'mG APPARATUS Thomas J. Radcliffe,Belleville, N. J., assigner to General Electric Company, a corporationoi' New York Application April 23, 1943, Serial No.' 484,219

` Claims.

My invention relates, in general, to apparatus for applying coatings toelectrically conductive strip and similar material. More particularly,my invention relates to apparatus for applying a coating ofglow-preventing material to selected portions of a metal strip fromwhich' glow lamp electrodes are to be later punched. The presentapplication is a continuation-impart of` my prior United Statesapplication Serial No. 449,027, filed June 29, 1942.

Glow discharge lamps comprising closely spaced electrodes mounted withina sealed envelope-are well-known in the art. A species of such lampscomprising two spaced, juxtapositioned electrodes shaped as quadrants of'a hollow sphere and so arranged as to jointly present a hemisphericalsurface is disclosed in United States Patent No. 1,965,586, issued Julyl0, 1934 to T. E. Foulke. This patent also discloses the use of aluminumor aluminum oxide, among other materials, for excluding the glowdischarge from the inner surface of the electrodes and confiningcomprising-my invention; Fig. 2 is a section on theline 2 2 of Fig. l;Fig. 3 is a, forward end view of the guiding and feed means of theapparatus comprising my invention as viewed fromv the line 3 3of Fig. 1;Fig. 4 is a longitudinal vertical section through the coating applicatormeans and associated parts, the section being taken on the line 4 4 ofFig. 3; Fig. 5 is a top view, partly in section, taken along the line 55 of Fig. 4; Fig. 6 is a vertical section taken on the line 6 6 of Fig.1; and Fig. 7 is a diagrammatic i wiring diagram showing the arrangementfor said discharge to the outer hemispherical surface thereof.Heretofore the aluminum or aluminum oxide, hereinafter calledanti-glowmaterial, has been painted on the inner surface of the electrodes byhand with a small brush. This is a slow, expensive method not suitablefor mass production, and one in which complete and uniform coverage ofthe desired surface is not always obtained.

'Ihe prior application mentioned hereinabove relates to the method ofmanufacturing such electrodes or cathodes while the present applicationrelates to apparatus for applying the antiglow material to a givenportion of the metal strip out of which the electrodes are to be shapedor punched.

One objectof my invention is to provide apparatus for applying a.coating to a given surface area of electrically conductive stripmaterial or the like.

y Another object of my invention is to'provide out impairing theductility of the metal supportl passing electrical current through thecoated metal strip.

Referring to the drawings, the machine there shown comprises verticallyspaced supply and collector reel holders I0, II, respectively, rotatablymounted on an upstanding support bracket I2 rigidly-secured to aninverted channel iron I3 bolted to the table portion I4 of a stationarystand or bed member I5. The two reel holders I0 and II each comprise apair of flanges or discs I6, II between which supply and take-up reelsor spools I8, I9, respectively, are held. The supply reel i8 on thelower or supply reel holder I0 is provided with a coil 2II of themetalstrip material 2|- to beprocessed 'or coated, and the said metalstrip 2| is drawn or pulled through the variousparts ofthe machine andthen wound up on the take-up or collector reel I9.

As shown in Fig. 2, the. two flanges I6, I1 of each reel holder I0, I Iare mounted on vertically-spaced horizontal shafts 22, 23, respectively,which are journaled in bearings 2l on the support bracket I2. The flangeI6 of each reel holder I0, Il is threaded onto its respective supportshaft 22 or 23 and is locked in position against rotation thereon by anut 25 threaded on the said shaft and screwed uptight against theflange.. Each of the threaded anges I 6 is provided with a smallconcentric boss or centering hub 25 on its inner side for centering thereels or spools I8, I9 in the reel holders I0, Il. The other flange Ilof each reel holder I0, II is slidably mounted on its respective supportshaft 22 or 23, the flange Il of the lower or supply reel holder I0being held in position on the shaft 22 by a retaining nut 21 threaded-on the shaft 22 and locked against ro,-

tation by a second or locking nut 28 threaded on the said shaft andscrewed up tight against the retaining nut 21. The said flange I1 of thesupply reel holder Il) is so positioned on the shaft 22 as to hold thesupply reel I8 loosely between the two flanges I6, I1 so as to permitfree rotation of the said reel on the reel holder I0. The flange I1 ofthe upper or collector reel holder Il is continuously urged against thecollector reel I9 thereon byaI compression coil spring 29 tting over theshaft '23'outwardly of the ange I1 and compressed between the said angeand a retaining nut 30 threaded on the shaft 23. The said re- `tainingnut 38 is locked against rotation or unloosenlng by a second' or lockingnut 3i threaded on the shaft 23.4

Thecollector reel holder II and the collector reel I9,mounted thereonare rotated in a clockwise direction, as viewed from the front of themachine .(Fig. I), by suitable means, as by an electric motor. 32connected through a speed reducer 33" to the shaft 23 of the collectorreel holder II. 'Ihe electric motor 32 and speed reducer 33 are xedlymounted on the machine stand or base I below the table I4 thereof andare interconnected by a belt 34 and pulleys 35, 36 on the motor andspeed reducer/shafts 37, 38, respectively. The shaft123 of the collectorreel holder I I is driven by the speed reducer 33 through suitabledrive' means, such as by a roller chain 39 and sprockets 40, 4I on therear ends of the speed 'reel holder Il may be considered as forming afriction or slipping clutch for driving the take-up reel I9.

As shown in Fig. 1, the metal strip 2l is continuously unwound from thesupply reel i3 by a pair of motor-driven feed rollers 4 2, 43 which feedthe metal strip'to a coating applicator device et comprising a coatingpot or tank 45 mounted on the channel I3 and containing a bath d6 of thecoating material (such as aluminum paint) tobe applied to the metalstrip. As the metal vInasniuchv as the take-up reel I9 is thereof. Thesaid feed rollers 42, 43 are preferably made of rubber and are providedwith shafts 55, 56, respectively, which are journaled in bearings 5'I inthe support bracket arms '52. The feed rollers are driven by the speedreducer 33 through suitable drive means, such as by a roller chain 58and sprockets 59, $0 on the speed reducer shaft 38 and the upper feedroller shaft 55, re-

spectively. The lower feed roller 43 is rotated ln a direction oppositeto that of the upper feed roller 42 by means of similar intermeshingspur gears 5I, '52 on the feed roller shafts 55. 56,'respectively.

Following its passage through the feed rollers d2, 43, the metal strip2i is next drawn under a front guide roller 63, thence over a coatingapplicator roller E4 which runs in the bath 46 of coating material, andthen under a rear guide roller 55. The front and rear guide rollers 63,35 are rotatably mounted on horizontal pins or shafts 66 supported inears 67, 61' on the coating pot 45 and are formed with annular groovesor channels 58 (Fig. 5) corresponding in width to the width of the metalstrip 2l so that the said strip is received therein as it passes underthe guide rollers 63, 65. The grooves 68 in the said guide rollers thusserve as guideways for laterally centering and directing the metal strip2l over the applicator roller S4. To permit the interchange of the guiderollers 6.3, 35 with other strip 2l is unwound'from the supply reel t8by n the feed rollers '42, 43, it is first drawn under a guide roller 4!rotatably mounted on an upstanding U-shaped support bracket 48 fastenedto the channel I3, the guide rcller 4l being mounted between theupstanding arms of the said bracket.

Fromthe guide roller 4l, the metal strip 2l is then drawnvinasubstantially horizontal direction by the feed rollers 42, 43 throughlateral guiding means 'in the. form of a. pair of laterally spaced guideplates or fingers :39, 49 (Fig. 3) between which the metal strip passes.'I'he said guide fingers 49, 49 extend at rightl angles to the metalstrip andfhave their inner.opposed ends notched, as indicated at 5o, toprovide a guide-v and proper guiding of metal strip of different widths,the roller support pins 8E are removably mounted in place in the supportears 6 1, 61', as by set screws 69 for instance.

The applicator roller 64, which maybe made of steel or which may have asteel surface, is rotatably mounted on a pin or shaft i0 having a head'1I at one end thereof and journaled in bearings 'I2 in the coating pot45..i The said roll-` er 54 is formed with a :dat edge or face 'i3narrower than the width of the metal strip 2l so that it applies an evencoating of the coating material or aluminum paint 46 along the centerportion of one side only (the underside) of the said strip as the stripis drawn over the applicator roller 84.

To permit the interchange lof the applicator roller 64 with otherrollers having faces 7130i holds the head II of the pin against theouter side of the coating pot 45, thus locking the pin in place in itsbearings 12. By moving the spring ill about its pivot point so as toclear the end of the pin 1t, the said pin can then be slid out of itsbearings I2 and a different sized applicator.

roller 64 substituted for the one theretofore in use.

The metal strip 2l is continuously pressed down against the applicatorroller 54 by a pressure roller 18 so that minor deviations in theflatness of the strip do not result in uneven coating thereof. The saidpressure roller 18 is preferably made of soft rubber and is rotatablymounted on a weighted lever or arm 11 pivoted on a pin 18 which issupported on the arms 82 of the feed roller support bracket The free endof the said lever 11 is provided with a ldepending U-shaped bracket 18which supports a pin' or shaft 88 on which the pressure rol-ler 18 islrotatably mounted. A weight 8|., fastened to the lever 11 (as by bolt82) at a point adjacent the free end thereof, insures the exertion ofsutilcient pressure on the metal strip by the pressure roller 18 tocausev the applicator roller 84 to rotate as the strip passes over it,thus bringing up a constant supply of the coating material from the bath48 for application to the continuously Y moving strip.

'I'he face 13 of the applicator roller 84 is made slightly narrower thanthe strip 2l to be coated so as to leave a narrow uncoated portion ateach side of the strip, thus avoiding any-possibility of the appliedcoating material 83 creeping or iiowing over the edges of the strip ontothe other side thereof. To insure the application of the coatingmaterial 46 to the strip 2i only up to the width of the roller face 13and in an even amount, the excess coating material carried up by theapplicator roller 84 is removed from the face 13 and sides 84 thereof bya wiper plate or blade 85 pivoted at one end on a pin 8B supported onthe coating pot ears 61 and resting at its other end on the face 13 ofthe applicator roller.` The free mounted on the stand I8 while theintermediate or second contact 88 is connected to the midpoint of thesecondary 88, as indicated in Fig. 7. The primary 88 of the transformer81 is connected across the terminals of a suitable source of alternatingcurrent, such as a 22o-volt, 60 cycle current source. I have found thata current of about 50 amperes through the ever-changing coated portionof the metal strip 2| bridging the contacts is effective for heating thesaid portion sufficiently to produce `an adherent, uniform baked-oncoating of aluminum paint on a nickel strip having. a width ofapproximately inch and a thickness of approximately 0.810 inch when thespeed of movement of the strip 2| over the contacts 88, 88 and 88 issuch that a given point accomplished, according to the invention, by

drawing the coated strip tightly, coated side out, over a seri of threevertically-spaced stationary contact drums 88, 88 and 88 whereby theuncoated side of the metal strip makes electrical contact withthe saiddrums. The contact drums 88, 88 and 88 are mounted on, and insulatedfrom, an upstanding support bracket or channel iron 8| fastened to thechannel iron I3 on the table |4. As shown inFig. 6, each of the saidcontacts 88, 88 and 88 are secured to the channel 8| by a bolt 82 andare insulated from the channel by a flanged bushing 83 and a washer 84both of suitable insulating material, preferably a plastic such as thatcommercially known as 'Iransite. To prevent the metal strip 2| fromsliding or creeping oi the contact drums 88, 88 and 88, each of the saiddrums is' provided with out-turned annular anges 85 at each side thereofwhich serve to guide and hold the metal strip in place A transformer 81capable of changing a 22o-volt current supply of commercial (S0-cycle)frequency to 2.5 volts between the midpoint and the opposite ends of thesecondary .88 is suitable for the above purpose.

While the center contact 88 and its connection to the transformersecondary may be omitted, I have found that it minimizes sparking at theend contacts 88 and 88 and is therefore desirable. Furthermore, the saidcenter contact 88 avoids overheating portions and underheating otherportions of the metal strip 2| at the beginning and at the end of a run.At such times, the machine is stopped and current passed through thatportionl of the strip which would not otherwise be suiiiciently crproperly heated. The center contact 88 avoids such undesired temperaturedistribution and thus eliminates spoilage of material.

After passing over the last contact drum 88, the `metal strip 2| is thendrawn over a anged sheave or idler pulley 88 rotatably mounted on a stud|88 extending from the support channel 8|. The said sheave guides thecoated strip 2| from the last contact 88 to the take-up or collectingreel I8 onto which the strip is then wound.

'I'he drive connections for the feed rollers .42, 43 and the collectorreel I8 are so arranged that the motor 32, acting through the frictionclutch formed by the stationary flange I6 and the spring-pressed ange I1 of the collector reel holder tends to rotate thecollector reel I8 at'a higher rate of speed than that of the feed rollers 42, 43 and to thuspull the metal strip 2| through the apparatus at a higher speed than thefeed rollers vwill allow. Sufncient tension is therefore exerted on theloop-like portion of the. strip 2| between the feed rollers 42, 43 andthe collector reel |8 to hold the said strip portion taut and firmlyagainst the electrical'contacts 88, 88 and 88 so as to avoid excessivesparking between the strip and the said contacts.

The strip 2| is continuously passed over and between the contacts 88, 88and 88 at a rate such that the coating material 83 is thoroughly bakedthereon without impairing the ductility of the strip for subsequentfabrication or shaping into articles such as the glow lamp electrodesreferred to hereinbefore. 'Ihis rate may be determined by trial runs ofthe apparatus.

Undue heating of the electrical contacts 88, 88 and 88, particularly thelast contact 88, by the hot portion of the strip 2| passing over itssurface may be prevented by providing sufficient heat dissipatingcapacity for the contacts. If the heat dissipating area of the contactitself is not suiiicient for this purpose, then heat radiating thealuminum paint sold by the Sahlin Chemical and Color Company of Camden,New Jersey, un-

' der the designation of No. 2056 Aluminum, is

eminently satisfactory for use as the coating 83 of anti-glow material.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. Apparatus for coating a metal strip with a bakable materialcomprising in combination, applicator means for applying the coatingmaterial to one side only of said strip,'electrical means comprisingspaced contacts for engaging with the uncoated side of said strip andfor passing electrical energy through said strip to heat it suicientlyto bake the coating thereon, and means for moving said stripsuccessively into effective relation to said applicator means and oversaid contacts. n

2. Apparatus for coating a metal strip with a bakable materialcomprising in combination, applicator means for applying the coatingmaterial to one side only of said strip, electrical means comprisingspaced *contactsl for engaging with the uncoated side of said strip andfor passing electrical energy through said strip to heat it suicientlyto bake the coating thereon, means lor moving said strip successivelyinto effective relation to said applicator means and over said contacts,and adjustable guide means for laterally aligning said .strip with saidapplicator means, said guide means providing a guide opening ofpreselectable width to accommodate strip said strip over said applicatorroller and thence over said contacts.

4. Apparatus for coating a metal strip with a layer of bakable coatingmaterial comprising applicator means for continuously applying thecoating material to a restricted mid-portion of one side only of thestrip, electrical means comprising spaced contacts for engaging with theuncoated side of the coated strip and -forpassing electrical energythrough said strip to heat it sufliciently to bake the coating materialthereon, and means for continuously moving said strip into effectivecoating relation to said applicator means and thence over said contacts,said lastnamed means exerting suiiicient tension on said strip to drawit taut and hold it firmly against the saidcontacts.

5. Apparatus for coating a metal strip with a layer of bakable coatingmaterial comprising applicator means for continuously applying thecoating material to one side only of the strip,

va plurality of spaced contacts for engaging with -the uncoated side ofthe coated strip, a transformer having a, secondary connected to saidcontacts to pass an electrical current through those portions of themetal strip which bridge the said contacts at a given instant, and meansfor continuously moving said strip into eiective nected to said contactsfor passing electrical encoating relation to said applicator means andthence over said contacts.

6. Apparatus for coating a-metal strip with av layer of bakable coatingmaterial comprising applicator means for continuously 'applying thecoating material to one side only of the strip, a set of threev spacedcontacts for successively engaging with the uncoated side of the coatedstrip, a transformer having a secondaryg the opposite ends of which areconnected to 'the first and -third ones of said contacts and anintermedial-.e point ycf which is connected to the inten mediate one ofsaid contacts, and means for continuously moving said strip intoeiective coating relation to said applicatorl means and thence over saidcontacts.

7. Apparatus for coating a'metal strip with a layer of bakable coatingmaterial comprising supply and collector reel holders for rotatablysupporting supply and collectorreels, roller-applicator means forcontinuously applying the coating material to one side only of thestrip,feedroller means for continuously drawing the metal strip oi the supplyreel and feeding it to said roller-applicator means, a plurality ofspaced contacts for enagging with the uncoated side of the coated strip,-a source of current supply connected to said contacts for passingelectrical energy through those portions of the metal strip which bridgethe said contacts at a given instant to heat the said strip portionssuiciently to bake the coating material thereon, and means including aslipping clutch for rotating said collector reel ata speed tending tocollect the metal strip faster than it is fed to the roller-applicatormeans by said feed-roller means whereby suilicient tension is exerted onthe coated portion of the strip to draw it taut and hold it rmly againstthe said contacts. s

8. Apparatus for coating a metahstrip with a layer of bakable coatingmaterial comprising supply and collector reel holders forrotatablysupporting supply and collector reels, a coating pot containing a bathof the-coating material to be applied to the strip, an applicator rollerrotatably mounted on said coating pot to run in said bath of coatingmaterial, said applicator roller having an applicating surface of awidth less than the width of said strip, feed-roller means forcontinuously drawing the strip off the supply reel and feeding it oversaid applicator roller, guide means for laterally aligning said stripwith respect to said applicator roller, a pressure roller for pressingsaid strip into rm contact with said applicator roller, a wiper platerest. ing on and straddling said applicator roller for removing excesscoating 'materialfrom the applicating surface and side walls lof theapplicator roller prior to the engagement of said applicating surfacewithsaid strip, a plurality of spaced contacts for engaging with theuncoated side of the coated strip, a source of currentsupply conergythrough those portions ofthe. metal strip which bridge the said contactsat a given instant to heat the said strip portions suiiciently to' bakethe coating material thereon, and means including a slipping clutch forrotating said collector reel at a speed tending to collect the metalstrip faster than it is fed to the said applicator roller 9. Apparatusfor coatinga metal strip with a bakable material comprising incombination, applicator means for applying the coating material to theunderside only of the strip while the latter is continuously advancedpast said applicator means in a transversely level position, andelectrical means comprising' spaced contacts for engagement with theuncoated side only of the advancing strip to thereby pass an electriccurrent through said strip to heatiit suiiciently to bake the coatingthereon.

10. Apparatus for coating a metal strip with a bakable materialcomprising in combination, ap-

plicator means for applying the coating material 1 to the strip whilethe latter is continuously advanced past said applicator means in atransversely level position, said applicator means applying the coatingmaterial to the underside onlyA to thereby pass an electric currentthrough said strip to heat it suiiciently to bake the coating thereon.

THOMAS J. RADCLIFFE.

